" (Friendship "with benefits" is a contemporary example.) Closely related to this is the invention of birth control.
There is too much that could be said here, so I'll be brief.
However, between the late 1800s and the first few decades of the 1900s the new system of "dating" added new stages to courtship.
One of the most obvious changes was that it multiplied the number of partners (from serious to casual) an individual was likely to have before marriage.
However, an extra layer, what we call "dating," has been added to the process of courting.